Crumbs!

"Crumb"
artisanbakers.com

"Crumb is a term that bakers use to define the inside of the bread. By looking at the way the cell structure of the crumb is formed, and the shape and size and color of the cells, a baker can analyze the hydration, flour types, and yeast amounts as well as how the dough was mixed and shaped. By looking at the shape and crust a baker can see how the bread was baked, flour types, fermentation balance, and moulding techniques...."

There's a comparison of machine-made and hand-crafted pullman loaves and baguette; and hydration levels. There's probably more to crumbs than that: but this page looks like a good place to start of study of the crumb.

Those loaves of bread are called pullman loaves. Whaddaya know!